There are many students reading books in the library. Boys account for 40%. Later, four boys came in. At this time, boys account for 7 / 16 of the total number. How many people were there in the library? Using X solution Formula: OK, if you want to score all OK, 5, 0.15.20 ~ 1OO

There are many students reading books in the library. Boys account for 40%. Later, four boys came in. At this time, boys account for 7 / 16 of the total number. How many people were there in the library? Using X solution Formula: OK, if you want to score all OK, 5, 0.15.20 ~ 1OO

There are x people in the library
0.4x+4=7/16(x+4)
7/16x-0.4x=9/4
35/80x=9/4
x=60
There were 60 people in the library
A: there were 60 people in the library